Apex domains cannot have CNAME records.
Question and response
Question
dig tangkas7.com. NS
Answer
tangkas7.com. 3 NS ns-1242.awsdns-27.org.
tangkas7.com. 3 NS ns-241.awsdns-30.com.
tangkas7.com. 3 NS ns-596.awsdns-10.net.
tangkas7.com. 3 NS ns-709.awsdns-24.net.
Authority
The response has no authority records.
Additional
. 0 OPT ; payload 1232, xrcode 0, version 0, flags 0